This invention is directed to propulsion systems for many types of vessels including cargo vessels, particularly, comprising a thrust tube propulsion system incorporating partially enclosed propellers.
Propulsion systems for hulled cargo vessels are well known in the prior art and generally employ externally located propellors. The hull of conventional cargo hull is designed to direct water flow around the bow along the vessel amidships and past the stern of the vessel. The underwater section of the hull is streamlined to reduce resistance of the vessel hull on movement through the water. Thrust is created by propellers normally located at the stern of the vessel. Additionally, some vessels are provided with externally located steering gear such as bow and stern thrusters, rudders, keels, bilge keels, skegs and kort nozzels. Consequently, conventional vessels, particularly large vessels, are not easily maneuverable in shallow water and require water draft of ten feet or so to avoid damaging the externally located steering gear. This problem is even more severe with large, flat bottom scows. The thrust tube propulsion system of the present invention overcomes the disadvantages of the prior art vessels by eliminating the external steering gear and thus providing a vessel which is maneuverable in shallow water.
It is therefore an object of this invention to provide a thrust propulsion system for a vessel which eliminates the need for externally located steering gear. One feature of this invention to provide a vessel which is manueverable in shallow water, even as little as twenty inches of water.
A resultant advantage of this invention to provide a vessel which reduces the water resistance occurring at the bow. The bow wave is markedly reduced. This is accomplished by a feature of the invention whereby water is drawn through longitudinally extending thrust tubes incorporated in the hull of the vessel, which tubes open at or near the bow to induct water flow, thereby reducing the water pushed to the side by the bow. Because the cargo vessel has a smaller bow wave, it is more economical to operate than conventional vessels.